sch_mqprio.c

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/*
 * net/sched/sch_mqprio.c
 *
 * Copyright (c) 2010 John Fastabend <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 */

#include <linux/types.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/module.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/sch_generic.h>

struct mqprio_sched {
    struct Qdisc        **qdiscs;
    int hw_owned;
};

static void mqprio_destroy(struct Qdisc *sch)
{
    struct net_device *dev = qdisc_dev(sch);
    struct mqprio_sched *priv = qdisc_priv(sch);
    unsigned int ntx;

    if (priv->qdiscs) {
        for (ntx = 0;
             ntx < dev->num_tx_queues && priv->qdiscs[ntx];
             ntx++)
            qdisc_destroy(priv->qdiscs[ntx]);
        kfree(priv->qdiscs);
    }

    if (priv->hw_owned && dev->netdev_ops->ndo_setup_tc)
        dev->netdev_ops->ndo_setup_tc(dev, 0);
    else
        netdev_set_num_tc(dev, 0);
}

static int mqprio_parse_opt(struct net_device *dev, struct tc_mqprio_qopt *qopt)
{
    int i, j;

    /* Verify num_tc is not out of max range */
    if (qopt->num_tc > TC_MAX_QUEUE)
        return -EINVAL;

    /* Verify priority mapping uses valid tcs */
    for (i = 0; i < TC_BITMASK + 1; i++) {
        if (qopt->prio_tc_map[i] >= qopt->num_tc)
            return -EINVAL;
    }

    /* net_device does not support requested operation */
    if (qopt->hw && !dev->netdev_ops->ndo_setup_tc)
        return -EINVAL;

    /* if hw owned qcount and qoffset are taken from LLD so
     * no reason to verify them here
     */
    if (qopt->hw)
        return 0;

    for (i = 0; i < qopt->num_tc; i++) {
        unsigned int last = qopt->offset[i] + qopt->count[i];

        /* Verify the queue count is in tx range being equal to the
         * real_num_tx_queues indicates the last queue is in use.
         */
        if (qopt->offset[i] >= dev->real_num_tx_queues ||
            !qopt->count[i] ||
            last > dev->real_num_tx_queues)
            return -EINVAL;

        /* Verify that the offset and counts do not overlap */
        for (j = i + 1; j < qopt->num_tc; j++) {
            if (last > qopt->offset[j])
                return -EINVAL;
        }
    }

    return 0;
}

static int mqprio_init(struct Qdisc *sch, struct nlattr *opt)
{
    struct net_device *dev = qdisc_dev(sch);
    struct mqprio_sched *priv = qdisc_priv(sch);
    struct netdev_queue *dev_queue;
    struct Qdisc *qdisc;
    int i, err = -EOPNOTSUPP;
    struct tc_mqprio_qopt *qopt = NULL;

    BUILD_BUG_ON(TC_MAX_QUEUE != TC_QOPT_MAX_QUEUE);
    BUILD_BUG_ON(TC_BITMASK != TC_QOPT_BITMASK);

    if (sch->parent != TC_H_ROOT)
        return -EOPNOTSUPP;

    if (!netif_is_multiqueue(dev))
        return -EOPNOTSUPP;

    if (!opt || nla_len(opt) < sizeof(*qopt))
        return -EINVAL;

    qopt = nla_data(opt);
    if (mqprio_parse_opt(dev, qopt))
        return -EINVAL;

    /* pre-allocate qdisc, attachment can't fail */
    priv->qdiscs = kcalloc(dev->num_tx_queues, sizeof(priv->qdiscs[0]),
                   GFP_KERNEL);
    if (priv->qdiscs == NULL) {
        err = -ENOMEM;
        goto err;
    }

    for (i = 0; i < dev->num_tx_queues; i++) {
        dev_queue = netdev_get_tx_queue(dev, i);
        qdisc = qdisc_create_dflt(dev_queue, &pfifo_fast_ops,
                      TC_H_MAKE(TC_H_MAJ(sch->handle),
                            TC_H_MIN(i + 1)));
        if (qdisc == NULL) {
            err = -ENOMEM;
            goto err;
        }
        priv->qdiscs[i] = qdisc;
    }

    /* If the mqprio options indicate that hardware should own
     * the queue mapping then run ndo_setup_tc otherwise use the
     * supplied and verified mapping
     */
    if (qopt->hw) {
        priv->hw_owned = 1;
        err = dev->netdev_ops->ndo_setup_tc(dev, qopt->num_tc);
        if (err)
            goto err;
    } else {
        netdev_set_num_tc(dev, qopt->num_tc);
        for (i = 0; i < qopt->num_tc; i++)
            netdev_set_tc_queue(dev, i,
                        qopt->count[i], qopt->offset[i]);
    }

    /* Always use supplied priority mappings */
    for (i = 0; i < TC_BITMASK + 1; i++)
        netdev_set_prio_tc_map(dev, i, qopt->prio_tc_map[i]);

    sch->flags |= TCQ_F_MQROOT;
    return 0;

err:
    mqprio_destroy(sch);
    return err;
}

static void mqprio_attach(struct Qdisc *sch)
{
    struct net_device *dev = qdisc_dev(sch);
    struct mqprio_sched *priv = qdisc_priv(sch);
    struct Qdisc *qdisc;
    unsigned int ntx;

    /* Attach underlying qdisc */
    for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
        qdisc = priv->qdiscs[ntx];
        qdisc = dev_graft_qdisc(qdisc->dev_queue, qdisc);
        if (qdisc)
            qdisc_destroy(qdisc);
    }
    kfree(priv->qdiscs);
    priv->qdiscs = NULL;
}

static struct netdev_queue *mqprio_queue_get(struct Qdisc *sch,
                         unsigned long cl)
{
    struct net_device *dev = qdisc_dev(sch);
    unsigned long ntx = cl - 1 - netdev_get_num_tc(dev);

    if (ntx >= dev->num_tx_queues)
        return NULL;
    return netdev_get_tx_queue(dev, ntx);
}

static int mqprio_graft(struct Qdisc *sch, unsigned long cl, struct Qdisc *new,
            struct Qdisc **old)
{
    struct net_device *dev = qdisc_dev(sch);
    struct netdev_queue *dev_queue = mqprio_queue_get(sch, cl);

    if (!dev_queue)
        return -EINVAL;

    if (dev->flags & IFF_UP)
        dev_deactivate(dev);

    *old = dev_graft_qdisc(dev_queue, new);

    if (dev->flags & IFF_UP)
        dev_activate(dev);

    return 0;
}

static int mqprio_dump(struct Qdisc *sch, struct sk_buff *skb)
{
    struct net_device *dev = qdisc_dev(sch);
    struct mqprio_sched *priv = qdisc_priv(sch);
    unsigned char *b = skb_tail_pointer(skb);
    struct tc_mqprio_qopt opt = { 0 };
    struct Qdisc *qdisc;
    unsigned int i;

    sch->q.qlen = 0;
    memset(&sch->bstats, 0, sizeof(sch->bstats));
    memset(&sch->qstats, 0, sizeof(sch->qstats));

    for (i = 0; i < dev->num_tx_queues; i++) {
        qdisc = netdev_get_tx_queue(dev, i)->qdisc;
        spin_lock_bh(qdisc_lock(qdisc));
        sch->q.qlen     += qdisc->q.qlen;
        sch->bstats.bytes   += qdisc->bstats.bytes;
        sch->bstats.packets += qdisc->bstats.packets;
        sch->qstats.qlen    += qdisc->qstats.qlen;
        sch->qstats.backlog += qdisc->qstats.backlog;
        sch->qstats.drops   += qdisc->qstats.drops;
        sch->qstats.requeues    += qdisc->qstats.requeues;
        sch->qstats.overlimits  += qdisc->qstats.overlimits;
        spin_unlock_bh(qdisc_lock(qdisc));
    }

    opt.num_tc = netdev_get_num_tc(dev);
    memcpy(opt.prio_tc_map, dev->prio_tc_map, sizeof(opt.prio_tc_map));
    opt.hw = priv->hw_owned;

    for (i = 0; i < netdev_get_num_tc(dev); i++) {
        opt.count[i] = dev->tc_to_txq[i].count;
        opt.offset[i] = dev->tc_to_txq[i].offset;
    }

    if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
        goto nla_put_failure;

    return skb->len;
nla_put_failure:
    nlmsg_trim(skb, b);
    return -1;
}

static struct Qdisc *mqprio_leaf(struct Qdisc *sch, unsigned long cl)
{
    struct netdev_queue *dev_queue = mqprio_queue_get(sch, cl);

    if (!dev_queue)
        return NULL;

    return dev_queue->qdisc_sleeping;
}

static unsigned long mqprio_get(struct Qdisc *sch, u32 classid)
{
    struct net_device *dev = qdisc_dev(sch);
    unsigned int ntx = TC_H_MIN(classid);

    if (ntx > dev->num_tx_queues + netdev_get_num_tc(dev))
        return 0;
    return ntx;
}

static void mqprio_put(struct Qdisc *sch, unsigned long cl)
{
}

static int mqprio_dump_class(struct Qdisc *sch, unsigned long cl,
             struct sk_buff *skb, struct tcmsg *tcm)
{
    struct net_device *dev = qdisc_dev(sch);

    if (cl <= netdev_get_num_tc(dev)) {
        tcm->tcm_parent = TC_H_ROOT;
        tcm->tcm_info = 0;
    } else {
        int i;
        struct netdev_queue *dev_queue;

        dev_queue = mqprio_queue_get(sch, cl);
        tcm->tcm_parent = 0;
        for (i = 0; i < netdev_get_num_tc(dev); i++) {
            struct netdev_tc_txq tc = dev->tc_to_txq[i];
            int q_idx = cl - netdev_get_num_tc(dev);

            if (q_idx > tc.offset &&
                q_idx <= tc.offset + tc.count) {
                tcm->tcm_parent =
                    TC_H_MAKE(TC_H_MAJ(sch->handle),
                          TC_H_MIN(i + 1));
                break;
            }
        }
        tcm->tcm_info = dev_queue->qdisc_sleeping->handle;
    }
    tcm->tcm_handle |= TC_H_MIN(cl);
    return 0;
}

static int mqprio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
                   struct gnet_dump *d)
    __releases(d->lock)
    __acquires(d->lock)
{
    struct net_device *dev = qdisc_dev(sch);

    if (cl <= netdev_get_num_tc(dev)) {
        int i;
        struct Qdisc *qdisc;
        struct gnet_stats_queue qstats = {0};
        struct gnet_stats_basic_packed bstats = {0};
        struct netdev_tc_txq tc = dev->tc_to_txq[cl - 1];

        /* Drop lock here it will be reclaimed before touching
         * statistics this is required because the d->lock we
         * hold here is the look on dev_queue->qdisc_sleeping
         * also acquired below.
         */
        spin_unlock_bh(d->lock);

        for (i = tc.offset; i < tc.offset + tc.count; i++) {
            qdisc = netdev_get_tx_queue(dev, i)->qdisc;
            spin_lock_bh(qdisc_lock(qdisc));
            bstats.bytes      += qdisc->bstats.bytes;
            bstats.packets    += qdisc->bstats.packets;
            qstats.qlen       += qdisc->qstats.qlen;
            qstats.backlog    += qdisc->qstats.backlog;
            qstats.drops      += qdisc->qstats.drops;
            qstats.requeues   += qdisc->qstats.requeues;
            qstats.overlimits += qdisc->qstats.overlimits;
            spin_unlock_bh(qdisc_lock(qdisc));
        }
        /* Reclaim root sleeping lock before completing stats */
        spin_lock_bh(d->lock);
        if (gnet_stats_copy_basic(d, &bstats) < 0 ||
            gnet_stats_copy_queue(d, &qstats) < 0)
            return -1;
    } else {
        struct netdev_queue *dev_queue = mqprio_queue_get(sch, cl);

        sch = dev_queue->qdisc_sleeping;
        sch->qstats.qlen = sch->q.qlen;
        if (gnet_stats_copy_basic(d, &sch->bstats) < 0 ||
            gnet_stats_copy_queue(d, &sch->qstats) < 0)
            return -1;
    }
    return 0;
}

static void mqprio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
{
    struct net_device *dev = qdisc_dev(sch);
    unsigned long ntx;

    if (arg->stop)
        return;

    /* Walk hierarchy with a virtual class per tc */
    arg->count = arg->skip;
    for (ntx = arg->skip;
         ntx < dev->num_tx_queues + netdev_get_num_tc(dev);
         ntx++) {
        if (arg->fn(sch, ntx + 1, arg) < 0) {
            arg->stop = 1;
            break;
        }
        arg->count++;
    }
}

static const struct Qdisc_class_ops mqprio_class_ops = {
    .graft      = mqprio_graft,
    .leaf       = mqprio_leaf,
    .get        = mqprio_get,
    .put        = mqprio_put,
    .walk       = mqprio_walk,
    .dump       = mqprio_dump_class,
    .dump_stats = mqprio_dump_class_stats,
};

static struct Qdisc_ops mqprio_qdisc_ops __read_mostly = {
    .cl_ops     = &mqprio_class_ops,
    .id     = "mqprio",
    .priv_size  = sizeof(struct mqprio_sched),
    .init       = mqprio_init,
    .destroy    = mqprio_destroy,
    .attach     = mqprio_attach,
    .dump       = mqprio_dump,
    .owner      = THIS_MODULE,
};

static int __init mqprio_module_init(void)
{
    return register_qdisc(&mqprio_qdisc_ops);
}

static void __exit mqprio_module_exit(void)
{
    unregister_qdisc(&mqprio_qdisc_ops);
}

module_init(mqprio_module_init);
module_exit(mqprio_module_exit);

MODULE_LICENSE("GPL");